1. Field of the Invention
The present invention relates to a recording head, an integrated circuit for driving the head, a circuit board for the head, and a recording apparatus and, more particularly, to those suitably applied to a recording head such as an ink-jet recording head, a heat-sensitive recording head, thermal head, or the like, which performs recording by utilizing heat produced by a resistor or the like, an integrated circuit for driving the head, a circuit board for the head, and a recording apparatus.
2. Related Background Art
Conventionally, a recording system for performing recording by utilizing heat energy has advantages such as very low noise output since it is a non-impact recording system, allowing an elongated structure by arraying a large number of recording elements, and the like. In recent years, the recording system of this type has received attention since it can be easily applied to a color recording system.
In particular, an ink-jet recording apparatus which utilizes heat as energy for forming an emission droplet can easily realize a high-density multi-nozzle structure. Thus, the ink-jet recording apparatus has a great advantage in that a high-resolution, high-quality image can be obtained at high speed.
In an ink-jet recording apparatus of this type, a plurality of droplet forming means for emitting ink droplets from emission ports upon application of heat energy to the ink, i.e., droplet forming means having electrothermal conversion elements which are heated upon reception of current pulses and can heat the ink, and a plurality of integrated circuits (driving ICs) for driving the electrothermal conversion elements are arranged on a single circuit board, thus constituting a recording head for a line printer, i.e., a so-called full-multi type recording head in which emission ports are arrayed over the total width of a recording medium.
FIG. 1 shows an electrical arrangement of an ink-jet recording head of this type, and FIG. 2 shows its driving timings. Recording data (SI), the number of bits of which correspond to the number of electrothermal conversion elements 7, are sequentially transmitted to shift registers 4 in driving ICs 3 in synchronism with a data transmission clock (CLK). After all the data are input, the input data are latched by latch circuits 5 in response to a latch signal (LAT). Thereafter, according to a divisional driving signal (EI) and a divisional driving signal transmission clock (ECK), the driving ICs 3 are sequentially enabled by flip-flops (F/F) 6, and the electrothermal conversion elements 7 whose recording data signals are ON are selectively energized during only an ON period of a pulse-width setting signal (ENB), thereby emitting droplets.
In a recording apparatus of this type, a data transmission direction of a recording data signal and a control signal is determined to be one direction. Therefore, when a mounting direction of a recording head is to be reversed, i.e., then the recording head is mounted at a position rotated through 180.degree. in a plane opposing a recording medium, new driving ICs must be manufactured, or the format of the data signal must be reconstructed in a reverse direction.
A case will be considered below wherein color recording is performed by an array of a large number of recording heads. An apparatus of this type ordinarily employs a divisional driving system in which emission ports are divided into blocks each including a predetermined number of ports, and heads are driven in units of blocks. In this system, the recording heads are mounted in the same direction to prevent dot offsets caused by shifted emission timings in the divisional driving mode and to have the same correspondences between color data and dot positions. However, in order to meet recent requirements of a compact recording apparatus, a demand has arisen for a structure which has a margin in mounting directions of heads. More specifically, in an arrangement wherein recording heads are mounted on the upper and lower surfaces of a single base plate to constitute a head unit, and, for example, two-color recording is performed by the head unit, a larger space can be advantageously assured as compared to a case wherein the heads are mounted on separate base plates.
In this case, however, the heads on the upper and lower surfaces have apparently opposite signal transmission directions, and a problem of dot offsets in the divisional driving mode may be posed. For example, assume that a recording apparatus comprises two arrays of recording heads each having emission ports aligned over a range corresponding to the total width of a recording medium, and performs divisional driving in the respective recording head while continuously conveying the recording medium. Steps having small stepped portions appear in a 1-line image due to divisional driving and continuous conveyance. However, as shown in FIG. 3, the steps appear in opposite directions since first and second heads have apparently opposite divisional driving directions. Thus, recording positions of upper and lower heads are offset from each other, and recording positions of upper and lower blocks overlap each other, resulting in color nonuniformity. In order to prevent this, two types of heads having different transmission directions are necessary, resulting in an economical disadvantage.
U.S. Pat. Nos. 4,463,359 and 4,520,373 disclose ink jet recording apparatuses wherein small recording heads are complementarily and alternately disposed at both sides of a common substrate, so as to constitute a full line recording head corresponding to the recording width along a conveying direction of the recording medium. These structures have an advantage in that a full line recording head can be readily obtained. They disclose a facsimile apparatus or copier wherein an original is read and information to be recorded is transmitted. However, they only disclose that time divisional driving is conducted equally for each small recording head, and that odd and even orders of the small recording heads are driven relating to a relative distance therebetween. As the reading means, a reading mechanism, wherein plurality of CCD's are disposed, such as a full line type 1 is disclosed. But, there is no disclosure concerning a concrete direction of a reading and a data transmission between a memory buffer and the recording head.
In case of an apparatus using reading means conducting reading for plural directions when the recording direction is fixed, it is necessary to change the address of reading data to be stored, or to change the address of the data supplied from the memory before driving the recording head. A structure for performing such address change operation would be complex.
Accordingly, in case of plural reading directions (i.e., bidirectional reading), it is important that the recording (data transmission) direction of each recording head constituting the full line head like ones disclosed in the above described U.S. Patents is adapted to the bidirectional high speed reading without increasing cost. Further, in case of a color recording wherein plural full line heads are disposed, it it important to achieve a high speed color recording without degrading image quality due to degrading of the color reproduction property and to recording position misalignment.